Expanding rotary bit



` R. N; FERGUSON EXPANDING ROTARY BIT Filed Oct. 24. 1925 Patented Aug.4 c 16, 1927.

APATENT oFFlcE.

noir N. FERGUSON, or Los ANGELES, cLrronNm.'

EXPANDING ROTARY Brr:

Appneaum'nrea october 24, 192s. serial No. 670,507.

My invention relates to the art of drilling oil wells, and is particularly applicable tg the rotary system of drilling. It is many times highly desirable in .ro-v tary drilling to be able to carry pipe, both for the purpose of holding up thewalls of` the well and for the purpose of controlling and directing the water circulation of the well. When pipe is so carried, it is necessary to employ a rotary bit which will pass through the pipe and which will cut ahole larger in diameter than the pipe.

It is an object of my invention to provide such a bit. l

The wear on rotary bits is very great and it is a further object of my' invention to provide a bit having remova le arcuate cutters which can be readily re laced. It is a still further ob]ect of my invention to provide 'a bit with rotary cutters which.

are easily fabricated.

Since rotary bits are subjected toV very heavy stresses, it is a further object of my -invention to provide a bit which is very rugged and strong. l

Further objects and advantages will be made evident hereinafter. v

Referring to the drawing which is. for illustrative purposes only, l Fig. l is a side edge elevation of a bit embodying my invention.

Fig. 2 is a side elevation of the same bit embodying myinvention.,

Fig. 3 is a view of the bit as seen from below.

Fig. 4 is a vertical sectional view take on the line 4`-4 of Fig. 1.

In the form of the invention illustrated, I employ a body 11 which is provided with a threaded pin 12 adapted to fit into a rotary tool joint. lProjecting .downwardly from f the body 11 are two legs 13,. having an'opening 14 therebetween. A water assage 16 extends dow'nwardl betweenfthe egs and communicates with t e space 14. A pin 20 having a head 21at one end passes between the legs, beingthreaded at the `ther end to engage a nut 22.' 'Mounted on the pin 20 be-` tween the legs 13 are cutting discs 23, these discs being circular in contour and having .to-said legs; and -a pair of cutting discs eca holefor the pin 20 eccentrically placed therein. The discs are shown in their cu-tting position in full lines in Fig. 2 and in their retracted position in dotted lines in that figure. It will be observed that the eccentric 5a mounting of the discs is so designed that when they are in their cutting position the axis of the pin 20 is slightly lower than the longitudinal axes of' thevdiscs. Theobject achieved .by this is that any hard formation on the side of the hole exerting a horizontal thrust in resistance toits abrasion will positively` lock the discs in their expanded position and assure a hole of' even diameter. The lower edges of the discs,when inhthe cutting position, are provided with a sharp ledge 25. The vopening 14 is shaped to pro.-

vide an upper curved abutment face 14 on each side gfthe body against which the upper portions of the respective discs may'abut when in their expanded. positions. The

opening 14 is further defined by curved engagement faces 15, one on each side of the body. These engagement faces are adapted to be engaged by the discs when in retracted position and serve, to prevent undesirablev -swinging of the discs or cramping of the discs in the wrong positions. 1

The method of operation is as follows:

' When it is desired to run the bit into the hole, the discs are turned into the position shown in dotted lines in Fig. 2, and' may then lbe run down through the pipe whichy it is desired to underream.v Whenever t-he discs strike the bottom of the hole, they turn into the osition shown in full lines in Fig. 2, being t ereby :'xpanded to cut a hole large y enough to allo-v the ,pipe to pass downwardly. 'The rotary mud is circulated through the opening 16 in the ordinary manner, or specia types o'f circulation or circa-- lating 'mediumniay be employed'.

I claim as my invention:

In a rotary bit, the combination of: `a body; apair of spaced legs extending downward from said body, a pair of abutment faces being formed between said legs, and apair of engagement faces being formed on` said body between said legs; a pip secured centrically mounted on said pin .between said legs in such a manner as to have a retracted position and an expanded cutting pov' sition, the peripheries of said dises being adapted to engage said engagement faces v vhen said discs are-in retracted positions and to engage said abutment .faces when in In testimony whereof, I have hereunto set .my hand at Los Angeles, California, this ,18th day of'oetoben 1923.

BOY N. FERGUSON. 

